Dynamic fracture damage mechanism and impact resistance of ceramics under impact load
摘要
This study experimentally investigates the fracture and damage characteristics of different ceramic targets under impact loading. The research finds that radial cracks form during the loading phase and extend during unloading, appearing earlier than circumferential cracks. The introduction of a steel backing plate enhances the stiffness of the target, inhibiting the generation of circumferential cracks but not altering the stress state on the front face of the ceramic. Micro-fracture mode analysis indicates that Al2O3 exhibits intergranular fracture characteristics, while B4C shows trans-granular fracture characteristics, and SiC exhibits both fracture modes. In terms of crack propagation dynamics, the path of conical cracks is regulated by both the internal stress field within the ceramic and the reflected tensile pulses, with the cone angle being independent of impact velocity but significantly influenced by ceramic thickness and material properties. Specifically, the radial crack propagation in Al2O3 behind the formation of the fractured cone, whereas in SiC and B4C, it is the opposite. It is noteworthy that the diameter of the perforation is only related to the size of the projectile head and the material’s shear strength, independent of thickness and impact velocity. Furthermore, the load variations among different ceramics at the same impact velocity are significantly different, primarily manifesting in the peak load and the dwell time of projectile. The study reveals the failure mechanisms and performance balance rules of different ceramic systems under dynamic loading, providing important theoretical basis for the optimization design of protective materials.